An electromechanically reconfigurable plasmonic metamaterial operating in the near-infrared
An electromechanically reconfigurable plasmonic metamaterial operating in the near-infrared
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DOI：
10.1038/nnano.2013.25
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发表时间：
2013-04-01
影响因子：
38.3
通讯作者：
Zheludev, Nikolay I.
中科院分区：
文献类型：
--
作者：
Ou, Jun-Yu;Plum, Eric;Zheludev, Nikolay I.
目前超材料研究的重点是获得动态功能，如电磁波的可调谐性、开关和调制(1)。为此，出现了各种方法，包括嵌入式变容管(2)，相变介质（3,4），液晶的使用（5,6），石墨烯（7,8）和超导体(9)的电调制，以及半导体衬底中的载流子注入或耗尽（10,11）。然而，在可见光和近红外范围内的调谐、开关和调制超材料特性仍然是主要的技术挑战：事实上，用于亚太赫兹（12）和太赫兹（13-15）区域的现有微电子机械解决方案不能缩小两到三个数量级以进入光谱范围。在这里，我们开发了一种新型的超材料，在光谱的光学部分工作，比以前报道的电可重构超材料快三个数量级。这种超材料是由静电力驱动的，只要在其纳米级结构块（等离子体元分子）上施加几伏电压，就能产生静电力。等离子体元分子由从纳米级厚度的柔性氮化硅膜上剪下的平行弦对支撑。这些皮克质量的弦，可以被同步驱动到兆赫兹频率，以机电方式重新配置超分子，并显著改变超材料的透射和反射光谱。这种超材料巨大的电光响应(约为10（-5)-10(-6)m V-1）允许其光学特性的快速连续调谐（高达8%的光信号调制，高达兆赫兹）或在只有100纳米厚的设备中进行高对比度不可逆切换，而无需外部偏振器和分析仪。
Current efforts in metamaterials research focus on attaining dynamic functionalities such as tunability, switching and modulation of electromagnetic waves(1). To this end, various approaches have emerged, including embedded varactors(2), phase-change media(3,4), the use of liquid crystals(5,6), electrical modulation with graphene(7,8) and superconductors(9), and carrier injection or depletion in semiconductor substrates(10,11). However, tuning, switching and modulating metamaterial properties in the visible and near-infrared range remain major technological challenges: indeed, the existing microelectromechanical solutions used for the sub-terahertz(12) and terahertz(13-15) regimes cannot be shrunk by two to three orders of magnitude to enter the optical spectral range. Here, we develop a new type of metamaterial operating in the optical part of the spectrum that is three orders of magnitude faster than previously reported electrically reconfigurable metamaterials. The metamaterial is actuated by electrostatic forces arising from the application of only a few volts to its nanoscale building blocks-the plasmonic metamolecules-that are supported by pairs of parallel strings cut from a flexible silicon nitride membrane of nanoscale thickness. These strings, of picogram mass, can be driven synchronously to megahertz frequencies to electromechanically reconfigure the metamolecules and dramatically change the transmission and reflection spectra of the metamaterial. The metamaterial's colossal electro-optical response (on the order of 10(-5)-10(-6) m V-1) allows for either fast continuous tuning of its optical properties (up to 8% optical signal modulation at up to megahertz rates) or high-contrast irreversible switching in a device only 100 nm thick, without the need for external polarizers and analysers.